import pandas as pd 
dict = {
    'name':['Tom','Bob','Mary','James'],
    'age':[18,30,25,40],
    'city':['Beijing','Shanghai','Guangzhou','Shenzhen']
}
df = pd.DataFrame(dict)
print(df)

df['country'] = 'China'
print(df)

df['country'] = ['China','China','USA','USA']
print(df)

df['adress'] = df['country']
print(df)

df['adress'] = df['city']+','+df['country']
print(df)

print(df.drop('country',axis=1))

del df['country']
print(df)

df.drop('city',axis=1,inplace=True)
print(df)

new_df = df[['age','name']]
df['name'] = '111'
print(df)
print(new_df)

df.columns=['Age','Name','Address']
print(df)